Himalaya to be eroded down to sea level?

12. Given that 1) the average density of the rock which comprises theHimalaya is 2.8 g/cm3, 2) the average density of lithospheric mantleis 3.3 g/cm3, 3) the maximum elevation of the Himalaya is 8.8 km,and 4) the average rate at which mountains are eroded is 0.2 mm/yr, calculatehow long it would take for the Himalaya to be eroded down to sea level. Showyour working.

Clue: You are provided with density data for a reason. Is it only 8.8 kmwhich needs to be eroded? What does Archimedes principle tell us?

Non-relevant ramblings

This reminds of something I read when I was quite young (maybe 10).

There is a block of granite, one mile long, one mile wide, and one mile high.
Every 1000 years, a small bird returns and rubs his beak on the block.
When the entire block is worn away, one day of eternity has passed.

It was a mind-expanding (and chilling) experience.

I tried to grasp the concept of "forever". . and later the concept of "infinity".
(I'm still working on it.)